1. Field of the Invention
The present invention relates to a dressing apparatus for conditioning and regenerating a chemical mechanical polishing (referred to as CMP hereafter) pad, and more particularly to a CMP machine dresser and method for detecting dislodgement of diamonds from the same.
2. Background
As densities of Integrated Circuits increase, the global planarization of the intermediate insulating layer has become important. CMP in particular has received special attention as a planarization method. Highly integrated semiconductor devices are manufactured by depositing conducting materials between insulating materials alternately to form patterns. The surface must be flat in order to apply the pattern layer.
As the semiconductor devices get more integrated, the miniaturization of features and multilevel interconnections are needed. Global planarization is one of the most important prerequisites to achieve this. As the structure of microprocessors and DRAMs becomes multileveled, problems may occur if the layers upon which the film is deposited are not flat. In the photolithography process in particular, if the process begins on an unflattened layer, incident light will reflect diffusely, which will cause an imprecise photo resist pattern. Planarization of the surface must take place by polishing the unnecessarily deposited areas.
Polishing pads must be cleaned after use due to residue. FIG. 1 shows a perspective view of a dressing apparatus, illustrating how it is integrated into a CMP device for wafer processes. As shown in FIG. 1, the dressing apparatus 10 includes a sleeve bearing mechanism 12, a carrier plate 14, and a plurality of dressers 16. The CMP device includes a rotating platform 20. A polish pad 22 is disposed on the rotating platform 20. Furthermore, the polishing pad 22 comprises a layer of microporous polyurethane material having an upward working surface 24. A wafer carrier 26 is used to carry a wafer 28 to be polished by the working surface 24 of the polishing pad 22 and a polishing slurry 30. The polishing slurry 30 is delivered onto the working surface 24 via a nozzle 32, whereby the porous polishing pad 22 is permeated with the polishing slurry 30.
FIG. 2 is a cross-section of the dresser 16. The dresser 16 includes a substrate 50, a plurality of diamonds 52, and a bonding layer 54, wherein the bonding layer 54 is used for mounting the diamonds 52 onto the substrate 50. In practice, however, some of the diamonds 52 fall off and attach to the working surface 24 of the polishing pad 22 in cleaning, thus causing wafers be damaged in subsequent polishing processes.